Continuous process for the recovery of 2 ethylhexanal and a tertiary amine from a mixture comprising 2-ethyl-2-(hydroxymethyl) hexanal, 2-ethylhexanal, tertiary amine and water

Abstract

Disclosed is a continuous process for the manufacture of 2-ethyl-2-(hydroxymethyl)hexanal wherein 2-ethylhexanal, formaldehyde and a tertiary amine are continuously fed to a reaction zone and crude product comprising an aqueous phase and an organic phase containing 2-ethyl-2-(hydroxymethyl)hexanal and 2-ethylhexanal is continuously removed from the reaction zone. Also disclosed are processes for (1) the azeotropic distillation of the organic phase of the crude product whereby unreacted 2-ethylhexanal is recovered and (2) the catalytic hydrogenation of the refined, organic phase of the crude product to produce 2-butyl-2-ethyl-1,3-propanediol.

We claim: 
     
       1. Continuous process for the recovery of 2-ethylhexanal and a tertiary amine from a mixture comprising ethyl 2-(hydroxymethyl)hexanal, 2-ethylhexanal, tertiary amine and water which comprises the steps of: (1) continuously feeding the mixture to the mid section of a distillation column;   (2) continuously feeding water to the middle or upper section of the distillation column;   (3) continuously removing from the distillation column a vapor stream comprising 2-ethylhexanal, tertiary amine and water;   (4) condensing the vapor stream of step (3) to obtain a two phase liquid and separating the organic phase rich in 2-ethylhexanal and tertiary amine; and   (5) continuously removing from the lower section of the distillation column a two phase mixture depleted in 2-ethylhexanal and tertiary amine and comprising 2-ethyl-2-(hydroxymethyl)hexanal and water.   
     
     
       2. Process according to claim 1 wherein the base of the distillation column is maintained at a temperature of about 100° to 110° C. and the tertiary amine is a trialkylamine having up to about 12 carbon atoms. 
     
     
       3. Process according to claim 1 for the recovery of 2-ethylhexanal and tertiary amine from a mixture comprising 2-ethyl-2-(hydroxymethyl)hexanal, 2-ethylhexanal, a tertiary amine and water which comprises the steps of: (1) continuously feeding the mixture to the mid-section of a distillation column, the base of which is maintained at a temperature of about 100° to 110° C.;   (2) continuously feeding water to the middle or upper section of the distillation column;   (3) continuously removing from the distillation column a vapor stream comprising 2-ethylhexanal, tertiary amine and water;   (4) condensing the vapor stream of step (3) to obtain a two phase liquid and separating the organic phase rich in 2-ethylhexanal and tertiary amine;   (5) continuously removing from the lower section of the distillation column a two phase mixture depleted in 2-ethylhexanal and tertiary amine and comprising 2-ethyl-2-(hydroxymethyl)hexanal and water; and   (6) separating the two phase mixture of step (5) into (i) an aqueous phase and (ii) an organic phase comprising at least 80 weight percent 2-ethyl-2-(hydroxymethyl)hexanal and less than 2 weight percent formaldehyde.   
     
     
       4. Process of claim 1 further comprising the steps of: (6) continuously separating the two phase mixture of step (5) into (i) an aqueous phase and (ii) an organic phase rich in 2-ethyl-2-(hydroxymethyl)-hexanal; and   (7) continuously feeding the organic phase of step (6) to a hydrogenation zone wherein the 2-ethyl-2-(hydroxymethyl)hexanal is contacted with a hydrogenation catalyst to produced 2-butyl-2-ethyl-1,3-propanediol.